How to Measure Wheel Fitment

If you're looking to install a new set of wheels and tires onto your vehicle, measuring will be required before placing an order. Don't worry, this process should not take long if done properly. Here are some important guidelines and additional things to consider when installing your wheels:

Getting Started

  • It's important to take your wheel measurements with the tire dismounted from the wheel in order to avoid mistakes.
  • Make sure to take your measurements with the suspension compressed (at normal ride height) and your vehicle on the ground.
  • Don't forget to take into account not only wheel size, but also clearance. Make sure your wheel/tire combo has clearance from suspension, exhaust or any other potential parts that may interfere with your ability to turn. A good way to do this is to compare to the previous wheel and tire on your vehicle.
  • If in doubt, you can use this Percy's WheelRite Wheel Fitment Tool to assure precision fitment of your wheels. We also suggest checking clearances BEFORE mounting tires on your new wheels.

What to Measure

In all, there are five dimensions you need to know in order to properly decide on a new set of wheels for your vehicle. Here's a look at what those dimensions are and how to measure each:

1. Diameter

This is the width of the wheel face. To get the diameter of a wheel, measure across the face of the wheel, not including the wheel lips — the part of the wheel designed to hold the tire in place.

2. Width

This is the depth of the wheel. It is measured from the inside of the wheel lip across the top of the wheel to the other lip. Once you have diameter and width, you'll have the basic dimensions needed to determine the apperance of your wheels.

3. Bolt Pattern

There are four common patterns — four-lug, five-lug, six-lug and eight-lug wheels. Depending on the pattern, the way you measure will change. You can use a JEGS Wheel/Stud Bolt Circle Template in order to accurately determine your bolt pattern.

4-lug

Measure from middle of any two bolt holes directly accross from one another.

5-lug

Choose two non-adjacent bolt holes. Measure from back of first hole to center of second hole.

6-lug

Measure from middle of any two holes directly accross from one another.

8-lug

Measure from middle of any two holes directly accross from one another.

4. Wheel Backspacing

This is measured from the rear of the mounting face to the backside wheel lip. Both backspacing and offset effect suspension and brake clearance.

Zero Offset

Hub mounting surface is generally flat and centered in the middle of the wheel. There is no need to measure here as the offset will be 0.

Negative Offset

Wheel has mounting surface closer to the back side of the wheel. Measure from the rear of the mounting face to centerline.

Positive Offset

Hub mounting surface is shallow, closer to the street side of the wheel. Measure from the rear of the mounting face to the centerline.

5. Wheel Offset

There are three common types of wheel offset you may encounter:

 

Zero Offset

Hub mounting surface is generally flat and centered in the middle of the wheel. There is no need to measure here as the offset will be 0.

Negative Offset

Wheel has mounting surface closer to the back side of the wheel. Measure from the rear of the mounting face to centerline.

Positive Offset

Hub mounting surface is shallow, closer to the street side of the wheel. Measure from the rear of the mounting face to the centerline.
Offset Comparison Chart
Wheel
Width		 Wheel Backspacing
3.25" 3.5" 4" 4.25" 4.5" 4.75" 5" 5.25" 5.5" 5.75" 6"
5.5" Wheel Width 5.5"Offset 0 +6mm +12mm +19mm +25mm +32mm +44mm +52mm +57mm +63mm +69mm
6" Wheel Width 6"Offset -6.4mm 0 +6mm +12mm +19mm +25mm +38mm +44mm +51mm +57mm +63mm
6.5" Wheel Width 6.5"Offset -12mm -6mm 0 +6mm +12mm +19mm +32mm +38mm +44mm +51mm +57mm
7" Wheel Width 7"Offset -19mm -12mm -6mm 0 +6mm +12mm +25mm +32mm +38mm +44mm +51mm
8" Wheel Width 8"Offset -32mm -25mm -19mm -12mm -6mm 0 +12mm +19mm +25mm +32mm +38mm
8.5" Wheel Width 8.5"Offset -38mm -32mm -25mm -19mm -12mm -6mm +6mm +12mm +19mm +25mm +32mm
9" Wheel Width 9"Offset -44mm -38mm -32mm -25mm -19mm -12mm 0 +6mm +12mm +19mm +25mm
9.5" Wheel Width 9.5"Offset -51mm -44mm -38mm -32mm -25mm -19mm -6mm 0 +6mm +12mm +19mm
10" Wheel Width 10"Offset -57mm -51mm -44mm -38mm -32mm -25mm -12mm -6mm 0 +6mm +12mm
10.5" Wheel Width 10.5"Offset -63mm -57mm -51mm -44mm -38mm -32mm -19mm -12mm -6mm 0 +6mm
11" Wheel Width 11"Offset -69mm -63mm -57mm -51mm -44mm -38mm -25mm -19mm -12mm -6mm 0
12" Wheel Width 12"Offset N/A N/A -69mm -63mm -57mm -51mm -38mm -32mm -25mm -19mm -6mm

Don't forget the lug nuts...

In addition to finding the right wheel fitment for your vehicle, it's important to make sure that you have the correct lug nuts to match so that wheel stays seated and centered properly and so you avoid vibration or loosening over time. There are several diffent styles of lug nut you need to be aware of when purchasing new wheels:

Conical Seat

Also known as "acorn" or "tapered", this is the most common seat type and is available with 60° or 45° taper.

Spherical Seat

Another common type of lug nut features a rounded or ball-shaped bottom which sits flush against the face of the wheel.

Mag Seat

Also known as "shank-style" this seat type has a shank which extends into the wheel. This style of lug nut generally uses a washer.

Extended Thread

Also called "ET", this type of lug nut is conical with a extended shank and is commonly found on older vehicles with shorter wheel studs.

Flange Style

Commonly found on ATVs, UTVs and other off-road, vehicles, this style features a small flange that can fit into a small recess on the wheel.

Metric Conversion Chart

Here are the comparable SAE (Society of Automotive Engineers) inch sizes for common metric lug nut sizes:

Metric Size SAE Size
100mm 3.94"
101.6mm 4"
114.3mm 4.5" (Ford & Mopar)
115mm 4.53"
120.65mm 4.75"(General Motors)
127mm 5" (Full-size & truck)
139.7mm 5.5" (Full-size & truck)
165.1mm 6.5"(6-lug & 8-lug truck)